diff --git a/src/uucore/Cargo.toml b/src/uucore/Cargo.toml
index 0fcf2021a..2148eb2d4 100644
--- a/src/uucore/Cargo.toml
+++ b/src/uucore/Cargo.toml
@@ -21,14 +21,16 @@ getopts = "<= 0.2.21"
 failure = { version = "<= 0.1.1", optional = true }
 failure_derive = { version = "<= 0.1.1", optional = true }
 time = { version = "<= 0.1.42", optional = true }
-data-encoding = { version = "^2.1", optional = true }
 libc = { version = "<= 0.2.66", optional = true }
 wild = "2.0.1"
 nix = { version = "<= 0.13", optional = true }
 lazy_static = { version = "1.3", optional = true }
 platform-info = { version = "<= 0.0.1", optional = true }
+## problem dependencies
 # * transitive dependency via 'failure'; pin to <= v0.3.30 to avoid increasing MinSRV to v1.33.0
 backtrace = ">= 0.3.3, <= 0.3.30"
+# * data-encoding: require 2.1, but 2.2.0 breaks the build for MinSRV 1.31.0
+data-encoding = { version = "~2.1", optional = true }
 
 [target.'cfg(target_os = "redox")'.dependencies]
 termion = "1.5"